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中国物理学会期刊

一种宽带可重构反射型极化旋转表面

CSTR: 32037.14.aps.67.20181041

Broadband reconfigurable reflective polarization convertor

CSTR: 32037.14.aps.67.20181041
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  • 将超材料设计思想与微电机系统(micro-electro-mechanical system,MEMS)技术相结合,提出了一种宽带可重构反射型极化旋转表面.该结构由上层方形金属贴片、中间介质层、金属底板以及连接贴片与底板的金属通孔构成,通过在电流短路点处加载MEMS开关,使其具有电可调特性.仿真结果表明,当MEMS开关导通时,该结构能在7.78 GHz–14.10 GHz频带内将入射的线极化波转化为正交极化波并反射;当MEMS开关断开时,入射波则以同极化全反射.加工了实际的样品并进行了测试,结果与仿真符合较好.该结构具有结构简单易加工、器件个数少、工作频带宽、损耗低等优点,在电磁波动态调控中具有潜在应用价值.

     

    With the rapid evolution of radar technology and mobile communication systems, polarization conversion has received much attention from academia and industry in recent years, which has the advantages of improving system performance through eliminating multipath fading. In this paper, a novel broadband reconfigurable reflective polarization convertor is designed, which combines the idea of metamaterial and the technology of micro-electro-mechanical system (MEMS) switches. The proposed structure consists of three layers: an upper metallic patches layer, a middle dielectric layer with a thickness of 2 mm, and a bottom metal plate. There are through-holes of metal connecting the upper and bottom layers. According to the simulation using HFSS software, when the MEMS switch is on, the device works with a relative bandwidth of 57.77% from 7.78 GHz to 14.10 GHz, of which the polarization conversion ratio is larger than 80%. In addition, at 7.62 GHz and 12.56 GHz, the reflected wave is a right-hand circularly polarized wave and a left-hand circularly polarized wave, respectively. When the MEMS switch is off, the reflected wave is in the same polarization, which means the device does not convert the polarization of electromagnetic wave anymore. The electromagnetic wave are decomposed into the u-v coordinate system to further understand the wideband polarization rotation. The reflection phase and the surface current distributions of the convertor are analyzed. Then, the working principle of polarization rotation is explained by analyzing the current distributions and explaining the theory from three different viewpoints. Finally, a 1225-cell (35×35) prototype is fabricated to verify the simulation results. The measured curve has three resonant frequencies and shifts towards the lower frequency slightly. The discrepancy between simulations and measurements is mainly attributed to the restriction of fabrication and measurement condition. In general, experimental results are in agreement with the simulations: when linear polarized wave is incident, the reflected wave realizes the transition from co-polarization to cross-polarization as the switch is switched from off to on. The proposed reconfigurable polarization rotation surface has advantages of broadband, low loss and ease of fabrication, which has great potential applications in antenna radiation, reducing the radar cross section and other territories in controlling electromagnetic wave dynamically.

     

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